Antigenic
Antigenic[edit | edit source]
An antigenic substance is any molecule or molecular structure that can be bound by an antibody or an antigen receptor on B cells or T cells. Antigens are typically proteins or polysaccharides, but they can be any type of molecule, including small molecules if they are attached to a larger carrier. The term "antigenic" refers to the property of being able to induce an immune response in the body, specifically the production of antibodies.
Types of Antigens[edit | edit source]
Antigens can be classified based on their origin:
- Exogenous antigens: These are antigens that have entered the body from the outside, for example, through inhalation, ingestion, or injection. The immune system responds to these antigens by producing antibodies.
- Endogenous antigens: These are antigens that are generated within the body, often as a result of normal cell metabolism or due to infection by a virus or bacteria. The immune system can recognize these antigens and mount a response.
- Autoantigens: These are normal proteins or complexes of proteins that are recognized by the immune system of patients with autoimmune diseases.
Antigenic Determinants[edit | edit source]
The specific part of an antigen that is recognized by the immune system is called an epitope or antigenic determinant. Each antigen can have multiple epitopes, allowing it to be recognized by different antibodies.
Antigenic Variation[edit | edit source]
Antigenic variation is a mechanism used by pathogens to evade the immune system. By altering their surface proteins, pathogens can avoid being recognized by antibodies that were produced in response to a previous infection. This is a common strategy used by viruses such as influenza and HIV.
Antigenic Shift and Drift[edit | edit source]
In the context of viruses, particularly the influenza virus, antigenic shift and drift are two processes that lead to changes in the virus's antigens:
- Antigenic drift: This refers to the gradual accumulation of mutations in the virus's genes that code for antigenic proteins. These small changes can lead to the virus evading the immune response generated by previous infections or vaccinations.
- Antigenic shift: This is a more dramatic change that occurs when two different strains of a virus infect the same cell and exchange genetic material. This can result in a new virus with a novel set of antigens, potentially leading to pandemics.
Also see[edit | edit source]
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